The present invention relates to a method of structurizing a knowledge processing system and a tool for structurizing the knowledge processing system.
A knowledge processing system generally comprises a knowledge base which stores therein knowledge coded in a machine-readable form for use in solving a problem and an inference program which uses the knowledge in a chaining fashion.
In contrast to the hitherto known problem solving program which is based on numerical processing for executing determinative algorithm processings, the knowledge processing system makes use of the knowledge given in a symbolic representation useful for solving a problem. This type of knowledge processing system is capable of dealing with empirical knowledge, know-how or heuristic knowledge such as those which the experts have acquired in various problem domains and which have been difficult to incorporate in the algorithms known heretoforce. For this reason, the knowledge processing system is increasingly employed widely not only for solving problems in the engineering field such as diagnosis, control, monitoring or supervision, planning and design but also in the field of legislation, money market and the like.
As methods of structurizing this knowledge processing system, there can be mentioned a method of establishing frame structures (conventions) for describing the knowledge and preparing the inference program using the knowledge in a chaining fashion with the aid of a symbol processing language such as LISP or PROLOG, and a method of using a knowledge processing system structurizing tool incorporating previously the knowledge describing frame structures and the inference program for using the frame structures. As a knowledge processing system structurizing tool, there are known "EMYCIN" described in Van Velle's "The Emycin Manual" contained in "The Stanford University Report No. STAN-CS-885", "ES/KERNEL" described in Kanamori et al's "Knowledge Representation Method and Rapid Inference Method in ES/KERNEL" contained in "HITACHI HYOURON", March 1987, pp. 17-22 and others. The first mentioned method is capable of setting up the knowledge representations, suited properly for solution of problems of concern and creation of inference programs. It is however noted that those who want to structurize the knowledge processing system is required to get skilled in the knowledge information processing technologies such as artificial intelligence, knowledge engineering or the like. Accordingly, it is difficult for those who are unaccustomed to these technological fields to structurize the knowledge processing system in accordance with the first mentioned method. On the other hand, the second mentioned method of utilizing the knowledge processing system structurizing tool does not require the preparation of the frame structures for knowledge representation and the inference program. However, the knowledge has to be described in such representation or expression which can be accepted by the knowledge processing system structurizing tool. Besides, for solving a problem of concern by resorting to the inference program, there is required examination of a method of composing the knowledge inputted as well as description of meta-knowledges for the inference control. Consequently, those who desire to structurize the knowledge processing system are required to be familiar with the knowledge concerning the object domain to which the problem to be solved pertains as well as the knowledge system structurizing tool to be used.
Such being the circumstances, there exists a great demand for development of such a method which allows even the unaccustomed person to structurize easily the knowledge processing system for solving a problem in the domain of concern (object domain).
In this regard, there is proposed by J. Laird and A. Newell a so-called general-purpose weak method in their article entitled "A Universal Weak Method: Summary of Results" 1983, Proceedings of the Eighth International Joint Conference on Artificial Intelligence. The proposed universal or general-purpose weak method is applied to solution of game problems. This method includes as the problem solving program (inference program) a plurality of weak methods based on a search procedure constituting a generic or universal problem solving procedure in various knowledge processing systems, wherein the knowledge processing system is structurized by establishing inference control knowledge proper to the domain of the problem to be solved. The abovementioned general-purpose weak method includes a plurality of weak methods including a hill-climbing method, a breadth-first search, a depth-first search and others.
The inventors of the present application have found after scrutinizing the universal or general-purpose weak methods the problems which will be elucidated below. The inventors started from a knowledge processing system structurizing tool created by applying the general-purpose (universal) weak method procedure. When a knowledge processing system is to be structurized for solving a problem with the aid of a conceived knowledge processing structurizing tool, the user of the knowledge processing system structurizing tool (hereinafter referred to simply as the user) selects a weak method to be made use of in solving the problem of concern. In that case, the user can certainly enjoy an advantage that the user can select the weak method suitable for solving the problem of concern, when compared with the case where the knowledge processing system is structurized by using the knowledge processing system structurizing tool described in "HITACHI HYOURON" mentioned hereinbefore. However, in order to structurize the knowledge processing system for solving a problem of concern by using the selected weak method, the user has to input the information by determining the inference control knowledges proper to a concerned problem to be solved as well as the inference control knowledge proper to the object domain to which the problem belongs. In that case, the information to be inputted is limited to the range improved by the selected weak method. However, it is extremely troublesome for the user to pay consideration to the knowledge such as mentioned above. It should additionally be mentioned that neither description nor suggestion is found in the article "A Universal weak Method" cited above concerning the inputting of the inference control knowledge proper to the concerned the problem to be solved and the knowledge proper to the object domain. The weak method to be selected naturally becomes different depending on the problems of concern. Consequently, such difficulty is encountered that another one of the inference control knowledge proper to the problem of concern and another one of the knowledge proper to the object domain have to be considered, respectively.
The knowledge processing system structurizing tool capable of utilizing the weak methods can certainly facilitate the structurization of the knowledge processing system by using that tool. However, the function of the inference program used in the structurized knowledge processing system is limited only to the functions of the existing weak methods incorporated in the structurizing tool.
As will be appreciated from the foregoing, it has been found that the knowledge processing system structurizing tool to which the conceived universal weak method is applied is incapable of structurizing the knowledge processing system for a given object domain and a given problem to be solved, because of the fact that the inference program of the structurized knowledge processing system is limited to the function of the existing weak method and that the inference control knowledge proper to the problem of concern and the knowledge proper to the domain which knowledge differ from one to another problem of concern have to be taken into consideration.